package netty.ch2;

import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelFutureListener;
import io.netty.channel.ChannelHandler;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
import io.netty.util.CharsetUtil;

@ChannelHandler.Sharable// ← --  标示一个Channel- Handler可以被多个Channel安全地共享
public class EchoServerHandler extends ChannelInboundHandlerAdapter {


    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) {
        ByteBuf in = (ByteBuf) msg;
        String data = in.toString();
        System.out.println(
            "Server received: " + in.toString(CharsetUtil.UTF_8));      //←--    将消息记录到控制台
        if (data.endsWith("\n")) {
            ctx.write(in); // ← --  将接收到的消息写给发送者，而不冲刷出站消息
        }

    }

    @Override
    public void channelReadComplete(ChannelHandlerContext ctx) {
        ctx.writeAndFlush(Unpooled.EMPTY_BUFFER)
            .addListener(ChannelFutureListener.CLOSE); //←--　将未决消息冲刷到远程节点，并且关闭该Channel
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx,
                                Throwable cause) {
        cause.printStackTrace();     //←--  打印异常栈跟踪
        ctx.close();//←--　关闭该Channel
    }
}
